Systems and methods for determining user input using position information  and force sensing

ABSTRACT

The embodiments described herein provide devices and methods that facilitate improved input device performance. Specifically, the devices and methods provide improved resistance to the effects of errors that may be caused by the motion of detected objects on such input devices, and in particular, to the effect of aliasing errors on input devices that use capacitive techniques to generate images of sensor values. The devices and methods provide improved resistance to the effects of aliasing errors by using force values indicative of force applied to the input surface. Specifically, the devices and methods use the force value to disambiguate determined position information for objects detected in the images of sensor values. This disambiguation of position information can lead to a reduction in the effects of aliasing errors and can thus improve the accuracy and usability of the input device.

PRIORITY CLAIM

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 61/619,344, filed Apr. 2, 2012

FIELD OF THE INVENTION

This invention generally relates to electronic devices, and morespecifically relates to input devices.

BACKGROUND OF THE INVENTION

Input devices including proximity sensor devices (also commonly calledtouchpads or touch sensor devices) are widely used in a variety ofelectronic systems. A proximity sensor device typically includes asensing region, often demarked by a surface, in which the proximitysensor device determines the presence, location and/or motion of one ormore input objects. Proximity sensor devices may be used to provideinterfaces for the electronic system. For example, proximity sensordevices are often used as input devices for larger computing systems(such as opaque touchpads integrated in, or peripheral to, notebook ordesktop computers, or as transparent sensor devices integrated withdisplay screens to provide a touch screen interface).

Many proximity sensor devices use capacitive techniques to sense inputobjects. Such proximity sensor devices may typically incorporate eitherprofile capacitive sensors or capacitive image sensors. Capacitiveprofile sensors alternate between multiple axes (e.g., x and y), whilecapacitive image sensors scan multiple transmitter rows to produce amore detailed capacitive “image” of “pixels” associated with an inputobject. While capacitive image sensors are advantageous in a number ofrespects, they do share some potential disadvantages.

Specifically, because of the time required to generate each capacitiveimage, image sensors can be sensitive to errors caused by quickly movingobjects. For example, aliasing errors may arise when sequential imagesshow input objects at different locations. In such cases it can bedifficult to determine if the detected input objects are the same inputobject or different input objects. Likewise, it can be difficult todetermine where a detected object first entered or later exited thesensing region. These aliasing errors can occur when objects are quicklymoving within or in and/or out of the sensing region. In such situationsthe proximity sensor device can incorrectly interpret the presence andmovement of such objects. Such errors can thus result in unwanted ormissed user interface actions, and thus can frustrate the user anddegrade the usability of the device.

Thus, while capacitive image proximity sensor devices are advantageousin a number of respects, there is a continuing need to improve theperformance of such devices. For example, to improve the responsivenessof such sensors, or to improve the sensor's resistance to errors, suchas aliasing errors.

Other desirable features and characteristics will become apparent fromthe subsequent detailed description and the appended claims, taken inconjunction with the accompanying drawings and the foregoing technicalfield and background.

BRIEF SUMMARY OF THE INVENTION

The embodiments of the present invention provide devices and methodsthat facilitate improved input device performance. Specifically, thedevices and methods provide improved resistance to the effects of errorsthat may be caused by the motion of detected objects on such inputdevices, and in particular, to the effect of aliasing errors on inputdevices that use capacitive techniques to generate images of sensorvalues. The devices and methods provide improved resistance to theeffects of aliasing errors by using force values indicative of forceapplied to the input surface. Specifically, the devices and methods usethe force value to disambiguate determined position information forobjects detected in the images of sensor values. This disambiguation ofposition information can lead to a reduction in the effects of aliasingerrors and can thus improve the accuracy and usability of the inputdevice.

In one embodiment, a processing system is provided for an input devicehaving a plurality of sensor electrodes, where the processing systemcomprises a sensor module and a determination module. The sensor modulecomprises sensor circuitry configured to operate the plurality of sensorelectrodes to generate images of sensor values indicative of objects ina sensing region proximate to an input surface at a first rate. Thesensor module is further configured to operate at least one force sensorto generate force values indicative of force applied to the inputsurface at a second rate. The determination module is configured todetermine if an input object detected in a first image of sensor valuesand an input object detected in a second image of sensor values remainedin contact with the input surface between the first image and the secondimage based at least in part on the force values. Such a determinationcan disambiguate the positional information for the detected objects,and thus can be used to improve the accuracy and usability of the inputdevice.

For example, such a determination can disambiguate whether such detectedobjects indicate a first object lifting from the input surface and asecond object being placed on the input surface, or instead indicatesthe same input object being moved across the input surface withoutlifting from the input surface. Such a disambiguation of positioninformation can lead improve the likelihood that the input device willrespond to the detected objects correctly, and thus can improve theaccuracy and usability of the input device.

In another embodiment, a processing system is provided for an inputdevice having a plurality of sensor electrodes, where the processingsystem comprises a sensor module and a determination module. The sensormodule comprises sensor circuitry configured to operate the plurality ofsensor electrodes to generate images of sensor values indicative ofobjects in a sensing region proximate to an input surface at a firstrate. The sensor module is further configured to operate at least oneforce sensor to generate force values indicative of force applied to theinput surface at a second rate. The determination module is configuredto determine an initial contact location for an input object firstdetected in a first image of sensor values based at least in part on atleast one force value preceding the first image of sensor values and thefirst image of sensor values. Such a determination can disambiguate thepositional information for the detected objects, and thus can be used toimprove the accuracy and usability of the input device.

For example, such a determination can disambiguate whether such adetected object had an initial contact location in a specified regionthat would indicate a specific user interface action. Such adisambiguation of position information can lead improve the likelihoodthat the input device will respond to the detected object correctly, andthus can improve the accuracy and usability of the input device.

BRIEF DESCRIPTION OF DRAWINGS

The preferred exemplary embodiment of the present invention willhereinafter be described in conjunction with the appended drawings,where like designations denote like elements, and:

FIG. 1 is a block diagram of an exemplary system that includes an inputdevice in accordance with an embodiment of the invention;

FIGS. 2A and 2B are block diagrams of sensor electrodes in accordancewith exemplary embodiments of the invention;

FIGS. 3A-3B are top and side views an exemplary input device and thatincludes at least one force sensor;

FIGS. 4-7 are schematic views of an exemplary input device with one ormore input objects in the sensing region; and

FIG. 8 is a schematic view of an input device showing various exemplaryobject positions.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Furthermore, there is no intention to be bound by anyexpressed or implied theory presented in the preceding technical field,background, brief summary, or the following detailed description.

Various embodiments of the present invention provide input devices andmethods that facilitate improved usability. FIG. 1 is a block diagram ofan exemplary input device 100, in accordance with embodiments of theinvention. The input device 100 may be configured to provide input to anelectronic system (not shown). As used in this document, the term“electronic system” (or “electronic device”) broadly refers to anysystem capable of electronically processing information. Somenon-limiting examples of electronic systems include personal computersof all sizes and shapes, such as desktop computers, laptop computers,netbook computers, tablets, web browsers, e-book readers, and personaldigital assistants (PDAs). Additional example electronic systems includecomposite input devices, such as physical keyboards that include inputdevice 100 and separate joysticks or key switches. Further exampleelectronic systems include peripherals such as data input devices(including remote controls and mice), and data output devices (includingdisplay screens and printers). Other examples include remote terminals,kiosks, and video game machines (e.g., video game consoles, portablegaming devices, and the like). Other examples include communicationdevices (including cellular phones, such as smart phones), and mediadevices (including recorders, editors, and players such as televisions,set-top boxes, music players, digital photo frames, and digitalcameras). Additionally, the electronic system could be a host or a slaveto the input device.

The input device 100 can be implemented as a physical part of theelectronic system, or can be physically separate from the electronicsystem. As appropriate, the input device 100 may communicate with partsof the electronic system using any one or more of the following: buses,networks, and other wired or wireless interconnections. Examples includeI²C, SPI, PS/2, Universal Serial Bus (USB), Bluetooth, RF, SMBus, andIRDA.

In FIG. 1, the input device 100 is shown as a proximity sensor device(also often referred to as a “touchpad” or a “touch sensor device”)configured to sense input provided by one or more input objects 140 in asensing region 120. Example input objects include fingers and styli, asshown in FIG. 1.

Sensing region 120 encompasses any space above, around, in and/or nearthe input device 100 in which the input device 100 is able to detectuser input (e.g., user input provided by one or more input objects 140).The sizes, shapes, and locations of particular sensing regions may varywidely from embodiment to embodiment. In some embodiments, the sensingregion 120 extends from a surface of the input device 100 in one or moredirections into space until signal-to-noise ratios prevent sufficientlyaccurate object detection. The distance to which this sensing region 120extends in a particular direction, in various embodiments, may be on theorder of less than a millimeter, millimeters, centimeters, or more, andmay vary significantly with the type of sensing technology used and theaccuracy desired. Thus, some embodiments sense input that comprises nocontact with any surfaces of the input device 100, contact with an inputsurface (e.g. a touch surface) of the input device 100, contact with aninput surface of the input device 100 coupled with some amount ofapplied force or pressure, and/or a combination thereof. In variousembodiments, input surfaces may be provided by surfaces of casingswithin which sensor electrodes reside, by face sheets applied over thesensor electrodes or any casings, etc. In some embodiments, the sensingregion 120 has a rectangular shape when projected onto an input surfaceof the input device 100.

The input device 100 also includes one or more force sensors that arecoupled to a surface below the sensing region 120 and the processingsystem 110, and configured to provide force values that are indicativeof force applied to the input surface (not shown in FIG. 1). The inputdevice 100 utilizes capacitive sensing to detect user input in thesensing region 120. To facilitate capacitive sensing, the input device100 comprises one or more sensing electrodes for detecting user input(not shown in FIG. 1).

Some implementations are configured to provide images that span one,two, three, or higher dimensional spaces. Some implementations areconfigured to provide projections of input along particular axes orplanes.

In some capacitive implementations of the input device 100, voltage orcurrent is applied to create an electric field. Nearby input objectscause changes in the electric field, and produce detectable changes incapacitive coupling that may be detected as changes in voltage, current,or the like.

Some capacitive implementations utilize arrays or other regular orirregular patterns of capacitive sensing elements to create electricfields. In some capacitive implementations, separate sensing elementsmay be ohmically shorted together to form larger sensor electrodes. Somecapacitive implementations utilize resistive sheets, which may beuniformly resistive.

Some capacitive implementations utilize “transcapacitive” sensingmethods. Transcapacitive sensing methods, sometimes referred to as“mutual capacitance”, are based on changes in the capacitive couplingbetween sensor electrodes. In various embodiments, an input object nearthe sensor electrodes alters the electric field between the sensorelectrodes, thus changing the measured capacitive coupling. In oneimplementation, a transcapacitive sensing method operates by detectingthe capacitive coupling between one or more transmitter sensorelectrodes (also “transmitter electrodes” or “transmitters”) and one ormore receiver sensor electrodes (also “receiver electrodes” or“receivers”). Transmitter sensor electrodes may be modulated relative toa reference voltage (e.g., system ground) to transmit transmittersignals. Receiver sensor electrodes may be held substantially constantrelative to the reference voltage to facilitate receipt of resultingsignals. A resulting signal may comprise effect(s) corresponding to oneor more transmitter signals, one or more conductive input objects,and/or to one or more sources of environmental interference (e.g. otherelectromagnetic signals). Sensor electrodes may be dedicatedtransmitters or receivers, or may be configured to both transmit andreceive.

In contrast, absolute capacitance sensing methods, sometimes referred toas “self capacitance”, are based on changes in the capacitive couplingbetween sensor electrodes and an input object. In various embodiments,an input object near the sensor electrodes alters the electric fieldnear the sensor electrodes, thus changing the measured capacitivecoupling. In one implementation, an absolute capacitance sensing methodoperates by modulating sensor electrodes with respect to a referencevoltage (e.g. system ground) to generate resulting signals on the sensorelectrodes. In this case, the resulting signals received on a sensorelectrode are generated by the modulation of that same sensor electrode.The resulting signals for absolute capacitive sensing thus comprise theeffects of modulating the same sensor electrode, the effects ofproximate conductive input objects, and the effects of and/or to one ormore sources of environmental interference. Thus, by analyzing theresulting signals on the sensor electrodes the capacitive couplingbetween the sensor electrodes and input objects may be detected.

Notably, in transcapacitive sensing the resulting signals correspondingto each transmission of a transmitter signal are received on differentsensor electrodes than the transmitter electrode used to transmit. Incontrast, in absolute capacitive sensing each resulting signal isreceived on the same electrode that was modulated to generate thatresulting signal.

In FIG. 1, processing system 110 is shown as part of the input device100. The processing system 110 is configured to operate the hardware ofthe input device 100 to detect input in the sensing region 120. Theprocessing system 110 comprises parts of or all of one or moreintegrated circuits (ICs) and/or other circuitry components. Forexample, as described above, the processing system 110 may include thecircuit components for operating the plurality of sensor electrodes togenerate images of sensor values indicative of objects in a sensingregion proximate to an input surface, and may also include circuitcomponents to operate at least one force sensor to generate force valuesindicative of force applied to an input surface.

In some embodiments, the processing system 110 also compriseselectronically-readable instructions, such as firmware code, softwarecode, and/or the like. In some embodiments, components composing theprocessing system 110 are located together, such as near sensingelement(s) of the input device 100. In other embodiments, components ofprocessing system 110 are physically separate with one or morecomponents close to sensing element(s) of input device 100, and one ormore components elsewhere. For example, the input device 100 may be aperipheral coupled to a desktop computer, and the processing system 110may comprise software configured to run on a central processing unit ofthe desktop computer and one or more ICs (perhaps with associatedfirmware) separate from the central processing unit. As another example,the input device 100 may be physically integrated in a phone, and theprocessing system 110 may comprise circuits and firmware that are partof a main processor of the phone. In some embodiments, the processingsystem 110 is dedicated to implementing the input device 100. In otherembodiments, the processing system 110 also performs other functions,such as operating display screens, driving haptic actuators, etc.

The processing system 110 may be implemented as a set of modules thathandle different functions of the processing system 110. Each module maycomprise circuitry that is a part of the processing system 110,firmware, software, or a combination thereof. In various embodiments,different combinations of modules may be used. Example modules includehardware operation modules for operating hardware such as sensorelectrodes and display screens, data processing modules for processingdata such as sensor signals and positional information, and reportingmodules for reporting information. Further example modules includesensor operation modules configured to operate sensing element(s) and adetermination module. In accordance with the embodiments describedherein, the sensor module may be configured to operate the plurality ofsensor electrodes to generate images of sensor values indicative ofobjects in a sensing region proximate to an input surface at a firstrate. The sensor module may be further configured to operate at leastone force sensor to generate force values indicative of force applied tothe input surface at a second rate. In one embodiment, the determinationmodule is configured to determine if an input object detected in a firstimage of sensor values and an input object detected in a second image ofsensor values remained in contact with the input surface between thefirst image and the second image based at least in part on the forcevalues. In another embodiment, the determination module may beconfigured to determine an initial contact location for an input objectfirst detected in a first image of sensor values based at least in parton at least one force value preceding the first image of sensor valuesand the first image of sensor values. In either case such adetermination can disambiguate the positional information for thedetected objects, and thus can be used to improve the accuracy andusability of the input device.

In some embodiments, the processing system 110 responds to user input(or lack of user input) in the sensing region 120 directly by causingone or more actions. Example actions include changing operation modes,as well as GUI actions such as cursor movement, selection, menunavigation, and other functions. In some embodiments, the processingsystem 110 provides information about the input (or lack of input) tosome part of the electronic system (e.g. to a central processing systemof the electronic system that is separate from the processing system110, if such a separate central processing system exists). In someembodiments, some part of the electronic system processes informationreceived from the processing system 110 to act on user input, such as tofacilitate a full range of actions, including mode changing actions andGUI actions.

For example, in some embodiments, the processing system 110 operates thesensing element(s) of the input device 100 to produce electrical signalsindicative of input (or lack of input) in the sensing region 120. Theprocessing system 110 may perform any appropriate amount of processingon the electrical signals in producing the information provided to theelectronic system. For example, the processing system 110 may digitizeanalog electrical signals obtained from the sensor electrodes. Asanother example, the processing system 110 may perform filtering orother signal conditioning. As yet another example, the processing system110 may subtract or otherwise account for a baseline, such that theinformation reflects a difference between the electrical signals and thebaseline. As yet further examples, the processing system 110 maydetermine positional information, recognize inputs as commands,recognize handwriting, and the like. In one embodiment, processingsystem 110 includes a determination module configured to determinepositional information for an input device based on the measurement.

“Positional information” as used herein broadly encompasses absoluteposition, relative position, velocity, acceleration, and other types ofspatial information. Exemplary “zero-dimensional” positional informationincludes near/far or contact/no contact information. Exemplary“one-dimensional” positional information includes positions along anaxis. Exemplary “two-dimensional” positional information includesmotions in a plane. Exemplary “three-dimensional” positional informationincludes instantaneous or average velocities in space. Further examplesinclude other representations of spatial information. Historical dataregarding one or more types of positional information may also bedetermined and/or stored, including, for example, historical data thattracks position, motion, or instantaneous velocity over time.

Likewise, the term “force values” as used herein is intended to broadlyencompass force information regardless of format. For example, the forcevalues can be provided for each object as a vector or scalar quantity.As other examples, the force information can also include time historycomponents used for gesture recognition. As will be described in greaterdetail below, the force values from the processing systems may be usedto disambiguate positional information for detected objects, and thuscan be used to improve the accuracy and usability of the input device.

In some embodiments, the input device 100 is implemented with additionalinput components that are operated by the processing system 110 or bysome other processing system. These additional input components mayprovide redundant functionality for input in the sensing region 120, orsome other functionality. FIG. 1 shows buttons 130 near the sensingregion 120 that can be used to facilitate selection of items using theinput device 100. Other types of additional input components includesliders, balls, wheels, switches, and the like. Conversely, in someembodiments, the input device 100 may be implemented with no other inputcomponents.

In some embodiments, the input device 100 comprises a touch screeninterface, and the sensing region 120 overlaps at least part of anactive area of a display screen. For example, the input device 100 maycomprise substantially transparent sensor electrodes overlaying thedisplay screen and provide a touch screen interface for the associatedelectronic system. The display screen may be any type of dynamic displaycapable of displaying a visual interface to a user, and may include anytype of light emitting diode (LED), organic LED (OLED), cathode ray tube(CRT), liquid crystal display (LCD), plasma, electroluminescence (EL),or other display technology. The input device 100 and the display screenmay share physical elements. For example, some embodiments may utilizesome of the same electrical components for displaying and sensing. Asanother example, the display screen may be operated in part or in totalby the processing system 110.

It should be understood that while many embodiments of the invention aredescribed in the context of a fully functioning apparatus, themechanisms of the present invention are capable of being distributed asa program product (e.g., software) in a variety of forms. For example,the mechanisms of the present invention may be implemented anddistributed as a software program on information bearing media that arereadable by electronic processors (e.g., non-transitorycomputer-readable and/or recordable/writable information bearing mediareadable by the processing system 110). Additionally, the embodiments ofthe present invention apply equally regardless of the particular type ofmedium used to carry out the distribution. Examples of non-transitory,electronically readable media include various discs, memory sticks,memory cards, memory modules, and the like. Electronically readablemedia may be based on flash, optical, magnetic, holographic, or anyother storage technology.

In accordance with various embodiments of the invention, the inputdevice 100 is configured with the processing system 110 coupled to aplurality of capacitive sensor electrodes and at least one force sensor.

In general, the input device 100 facilitates improved performance.Specifically, The input device 100 provides resistance to the effects oferrors that may be caused by the motion of detected objects, and inparticular, to the effect of aliasing errors that can be caused by thecapacitive techniques to generate images of sensor values. The inputdevice 100 provides improved resistance to the effects of aliasingerrors by using force values indicative of force applied to the inputsurface. Specifically, the processing system 110 uses force values todisambiguate determined position information for objects detected in theimages of sensor values.

In one embodiment, a processing system 110 is coupled to plurality ofsensor electrodes and at least one force sensor. In one embodiment, theprocessing system 110 comprises a sensor module and a determinationmodule. The processing system 110 is configured to operate the pluralityof sensor electrodes to generate images of sensor values indicative ofobjects in a sensing region proximate to an input surface at a firstrate. The processing system 110 is further configured to operate atleast one force sensor to generate force values indicative of forceapplied to the input surface at a second rate. In one embodiment, thesecond rate is greater than the first rate, and specifically the secondrate may be more than twice the first rate. In one embodiment, theprocessing system 110 is configured to determine if an input objectdetected in a first image of sensor values and an input object detectedin a second image of sensor values remained in contact with the inputsurface between the first image and the second image based at least inpart on the force values. In another embodiment, the processing system110 is configured to determine an initial contact location for an inputobject first detected in a first image of sensor values based at leastin part on at least one force value preceding the first image of sensorvalues and the first image of sensor values.

In either case such a determination can disambiguate the positionalinformation for the detected objects, and thus can be used to improvethe accuracy and usability of the input device 100.

As was described above, the processing system 110 is coupled to sensorelectrodes to determine user input. Specifically, the processing systemoperates by detecting the capacitive coupling between one or moretransmitter sensor electrodes and one or more receiver sensorelectrodes. Turning now to FIG. 2, these figures conceptually illustrateexemplary sets of capacitive sensor electrodes configured to sense in asensing region. Specifically, FIG. 2A shows electrodes 200 in arectilinear arrangement, while FIG. 2B shows electrodes 225 in aradial/concentric arrangement. However, it will be appreciated that theinvention is not so limited, and that a variety of electrode shapes andarrangements may be suitable in any particular embodiment.

Turning now to FIG. 2A, in the illustrated embodiment the capacitivesensor electrodes 200 comprise first sensor electrodes 210 and secondsensor electrodes 220. Specifically, in the illustrated embodiment, thefirst sensor electrodes 210 comprise six electrodes 210-1 to 210-6, andthe second sensor electrodes 220 comprise six electrodes 220-1 to 220-6.Each of the first sensor electrodes 210 is arranged to extend along asecond axis. Specifically, each first sensor electrode 210 has a majoraxis that extends along the second axis. It should also be noted thatthe first sensor electrodes 210 are distributed in an array, with eachof the first sensor electrodes 210 positioned a distance from adjacentfirst sensor electrodes 210 and corresponding to a different position inthe first axis.

Likewise, each of the second sensor electrodes 220 is arranged to extendalong a first axis, where the first and second axes are different axis.Specifically, each second sensor electrode 220 has a major axis thatextends along the first axis. It should also be noted that the secondsensor electrodes 220 are distributed in an array, with each of thesecond sensor electrodes 220 positioned a distance from adjacent secondsensor electrodes 220 and corresponding to a different position in thesecond axis.

Sensor electrodes 210 and 220 are typically ohmically isolated from eachother. That is, one or more insulators separate sensor electrodes 210and 220 and prevent them from electrically shorting to each other. Insome embodiments, sensor electrodes 210 and 220 are separated byinsulative material disposed between them at cross-over areas; in suchconstructions, the sensor electrodes 210 and/or sensor electrodes 220may be formed with jumpers connecting different portions of the sameelectrode. In some embodiments, sensor electrodes 210 and 220 areseparated by one or more layers of insulative material. In some otherembodiments, sensor electrodes 210 and 220 are separated by one or moresubstrates; for example, they may be disposed on opposite sides of thesame substrate, or on different substrates that are laminated together.The capacitive coupling between the transmitter electrodes and receiverelectrodes change with the proximity and motion of input objects in thesensing region associated with the transmitter electrodes and receiverelectrodes.

In transcapacitive sensing, the sensor pattern is “scanned” to determinethe capacitive couplings between transmitter and receiver electrodes.That is, the transmitter electrodes are driven to transmit transmittersignals and the receiver electrodes are used acquire the resultingsignals. The resulting signals are then used to determine measurementsof the capacitive couplings between electrodes, where each capacitivecoupling between a transmitter electrode and a receiver electrodeprovides one “capacitive pixel”. A two-dimensional array of measuredvalues derived from the capacitive pixels form a “capacitive image”(also commonly referred to as a “capacitive frame”) representative ofthe capacitive couplings at the pixels. Multiple capacitive images maybe acquired over multiple time periods, and differences between themused to derive information about input in the sensing region. Forexample, successive capacitive images acquired over successive periodsof time can be used to track the motion(s) of one or more input objectsentering, exiting, and within the sensing region.

A detailed example of generating images of sensor values will now begiven with reference to FIG. 2A. In this detailed example sensor valuesare generated on a “column-by-column”, with the first resulting signalsfor each column captured substantially simultaneously. Specifically,each column of resulting signals is captured at a different time, andtaken together are used to generate the first image of sensor values. Inthe embodiment of FIG. 2A, a transmitter signal may be transmitted withelectrode 210-1, and first resulting signals captured with each of thereceiver electrodes 220-1 to 220-6, where each first resulting signalcomprises effects of the first transmitter signal. These six firstresulting signals comprise a set (corresponding to a column) of firstresulting signals that may be used to generate the first image of sensorvalues. Specifically, from each of these six first resulting signalsprovides a capacitive measurement that corresponds to a pixel in thefirst capacitive image, and together the six pixels make up a column inthe first capacitive image.

Another transmitter signal may then be transmitted with electrode 210-2,and again first resulting signals may then be captured with each of thereceiver electrodes 220-1 to 220-6. This comprises another column offirst resulting signals that may be used to generate the first image.This process may be continued, transmitting from electrodes 210-3,210-4, 210-5 and 210-6, with each transmission generating another columnof first resulting signals until the complete first image of sensorvalues is generated.

It should next be noted that this is only one example of how such acapacitive image of sensor values can be generated. For example, suchimages could instead be generated on a “row-by row” basis usingelectrodes 220 as transmitter electrodes and electrodes 210 as receiverelectrodes. In any case the images of sensor values can be generated andused to determine positional information for objects in the sensingregion.

Next should be noted that in some embodiments the sensor electrodes 210and 220 are both configured to be selectively operated as receiverelectrodes and transmitter electrodes, and may also be selectivelyoperated for absolute capacitive sensing. Thus, the sensor electrodes210 may be operated as transmitter electrodes while the sensorelectrodes 220 are operated as receiver electrodes to generate the imageof sensor values. Likewise, the sensor electrodes 220 may be operated astransmitter electrodes while the sensor electrodes 210 are operated asreceiver electrodes to generate images to generate the image sensorvalues. Finally, sensor electrodes 210 and 220 may be selectivelymodulated for absolute capacitive sensing.

It should next be noted again that while the embodiment illustrated inFIG. 2A shows sensor electrodes arranged in a rectilinear grid, that isthis is just one example arrangement of the electrodes. In anotherexample, the electrodes may be arranged to facilitate positioninformation determination in polar coordinates (e.g., r, Θ). Turning nowto FIG. 2B, capacitive sensor electrodes 225 in a radial/concentricarrangement are illustrated. Such electrodes are examples of the typethat can be used to determine position information in polar coordinates.

In the illustrated embodiment, the first sensor electrodes 230 comprise12 electrodes 230-1 to 230-12 that are arranged radially, with each ofthe first sensor electrodes 230 starting near a center point andextending in different radial directions outward. In the illustratedembodiment the second sensor electrodes 240 comprise four electrodes240-1 to 240-4 that are arranged in concentric circles arranged aroundthe same center point, with each second sensor electrode 240 spaced atdifferent radial distances from the center point. So configured, thefirst sensor electrodes 230 and second sensor electrodes 240 can be usedto generate images of sensor values.

As described above, generating image of sensor values is relativelyprocessing intensive. For example, using transcapacitive sensing to scanthe capacitive couplings either on a “row-by-row” or “column-by-column”basis generally requires significant time and processing capabilitybecause each row and/or column in the image is generated separately.Furthermore, the rate at which each row or column can be scanned may befurther limited by the relatively large RC time constants in some inputdevice sensor electrodes. Furthermore, in typical applications multiplecapacitive images are acquired over multiple time periods, anddifferences between them used to derive information about input in thesensing region. For all these reasons, the rate at which images ofsensor values can be generated may be limited.

As was described above, because of the time required to generate eachcapacitive image, image sensors can be sensitive to errors caused byquickly moving objects. For example, aliasing errors may arise whensequential images show input objects at different locations. In suchcases it can be difficult to determine if the detected input objects arethe same input object or different input objects. Likewise, it can bedifficult to determine where a detected object first entered or laterexited the sensing region.

Returning to FIG. 1, as was noted above the processing system 110 isfurther configured to operate at least one force sensor to generateforce values that are indicative of force applied to an input surface.In general, the one or more force sensors are coupled to a surface andare configured to provide a plurality a measures of force applied to thesurface. Such force sensor(s) can be implemented in a variety ofdifferent arrangements. To give several examples, the force sensor(s)can be implemented as multiple force sensors arranged near a perimeterof the sensing region 120. Furthermore, each of the force sensors can beimplemented to measure compression force, expansion force, or both, asit is applied at the surface. Finally, a variety of differenttechnologies can be used to implement the force sensors. For example,the force sensors can be implemented with variety of differenttechnologies, including piezeoelectric force sensors, capacitive forcesensors, and resistive force sensors.

In general, the force sensor(s) operate to provide signals to theprocessing system 110 that are indicative of force. The processingsystem 110 may be configured to perform a variety of actions tofacilitate such force sensing. For example, the processing system 110may perform a variety of processes on the signals received from thesensor(s). For example, processing system 110 may select or coupleindividual force sensor electrodes, calibrate individual force sensors,and determine force measurements from data provided by the forcesensors.

Turning now to FIGS. 3A and 3B, examples of input objects in a sensingregion and applying force to a surface are illustrated. Specifically,FIGS. 3A and 3B show top and side views of an exemplary input device300. In the illustrated example, user's finger 302 and provides input tothe device 300. Specifically, the input device 300 is configured todetermine the position of the finger 302 and other input objects withinthe sensing region 306 using a sensor. For example, using a plurality ofelectrodes (e.g., electrodes 210 and 220 of FIG. 2A) configured tocapacitively detect objects such as the finger 302, and a processorconfigured to determine the position of the fingers from the capacitivedetection.

In accordance with the embodiments of the invention, the input device300 is further configured include one or more force sensor(s) 310.Specifically, one or more force sensor(s) 310 are arranged about thesensing region 306. Each of these force sensor(s) provides a measure ofthe force applied to the surface 308 by the fingers. Each of theseindividual force sensors can be implemented with any suitable forcesensing technology. For example, the force sensors can be implementedwith piezeoelectric force sensors, capacitive force sensors, and/orresistive force sensors. It should be noted that while the forcesensor(s) 310 are illustrated as being arranged around the perimeter ofthe sensing region 306 that this is just one example configuration. Asone example, in other embodiments a full array of force sensors 310could be provided to generate an “image” of force values.

The force sensor(s) are configured to each provide a measure of theforce applied to the surface. A variety of different implementations canbe used to facilitate this measurement. For example, the sensing elementof the force sensor can be directly affixed to the surface. For example,the sensing element can be directly affixed to the underside of thesurface or other layer. In such an embodiment, each force sensor canprovide a measure of the force that is being applied to the surface byvirtue of being directly coupled to the surface. In other embodiments,the force sensor can be indirectly coupled to the surface. For example,through intermediate coupling structures that transfer force,intermediate material layers or both. In any such case, the forcesensors are again configured to each provide a measure of the forceapplied to the surface. In yet other embodiments the force sensors canbe configured to directly detect force applied by the input objectitself, or to a substrate directly above the force sensors.

In one specific example, the force sensor(s) can be implemented ascontact—no contact sensors by being configured to simply indicate whencontact is detected. Such a contact—no contact sensor can be implementedwith a force sensor that identifies contact when detected force is abovea specified threshold, and provides a simply binary output indicatingthat such contact has been detected. Variations in such contact—nocontact sensors include the use of hysteresis in the force thresholdsused determine contact. Additionally, such sensors can use averaging ofdetected force in determining if contact is occurring.

In general it will be desirable to position each of the plurality offorce sensors near the perimeter edge of the sensor and to space thesensors to the greatest extent possible, as this will tend to maximizethe accuracy of the sensing measurements. In most cases this willposition the sensors near the outer edge of the sensing region. In othercases it will be near the outer edge of the touch surface, while thesensing region may extend beyond the surface for some distance. Finally,in other embodiments one or more the sensors can be positioned in theinterior of the sensor.

In the example of FIG. 3, four force sensors 310 are positioned near theperimeter of the rectangular sensing region 306 and beneath the surface308. However, it should be noted that this is just one exampleconfiguration. This, in other embodiments fewer or more of such sensorsmay be used. Furthermore, the sensors may be located in a variety ofdifferent positions beneath the surface 308. Thus, it is not necessaryto locate the force sensors near the corners or perimeters of thesurface 308.

It should be noted that many force sensors can be used to generate forcevalues at relatively high rates compared to the rates at which images ofsensor values can be generated. For example, in capacitive force sensorseach force sensor can generate a forced value with relatively fewcapacitive measurements compared to the number of capacitivemeasurements required for each image, and thus force values can begenerated at a relatively higher rate compared to rate at which imagesof sensor values can be generated. As will be described in greaterdetail below, the faster rate at which force values can be generated maybe used to reduce errors in the positional information determined by thesensor. Specifically, the embodiments described herein can use thefaster rate of force values to provide improved resistance to theeffects of errors that may be caused by the motion of detected objects,and in particular, to the effect of aliasing errors. In such embodimentsthe faster rate of force values are used disambiguate determinedposition information for objects detected in the images of sensorvalues. This disambiguation of position information can lead to areduction in the effects of aliasing errors and can thus improve theaccuracy and usability of the input device. Furthermore, in otherembodiments the force sensors can be provided to generate force valuesat the same rate at which capacitive images are generated. In theseembodiments it will be generally desirable to control the force sensorssuch that the force values are generated between images such that theforce values provide information regarding the contact of input objectsbetween such images.

So configured, the at least one force sensors operate to generate forcevalues that are indicative of force applied to the surface 308. As willnow be described in detail, in the various embodiments the processingsystem is configured to determine if an input object detected in a firstimage of sensor values and an input object detected in a second image ofsensor values remained in contact with the input surface between thefirst image and the second image based at least in part on these forcevalues. In various other embodiments the processing system is configuredto determine an initial contact location for an input object firstdetected in a first image of sensor values based at least in part on atleast one force value preceding the first image of sensor values and thefirst image of sensor values. It should be noted that in determining aninitial contact location calculating the actual location of initialcontact is not required. Instead, in many cases all that is needed todetermine an initial contact location is to determine if the initialcontact was within a certain region or within a threshold distance ofsome location. Such an example will be described in greater detailbelow.

Turning now to FIGS. 4 and 5, the input device 300 is illustrated withtwo different exemplary input object scenarios. In FIG. 4, an inputobject (i.e., a finger 402) is illustrated moving across the sensingregion 306 from a first position to a second position while remaining incontact with the surface 308. In FIG. 5, two input objects (i.e., finger502 and finger 504) are shown, where finger 502 is being lifted from thesurface 308 at the first position and shortly thereafter the finger 504is placed at the surface in the second position.

It should be appreciated that when either scenario occurs within asufficiently short time period, the input device 300 will effectivelydetect an image with a finger in the first position followed by an imagewith a finger in the second position. Without more information, theinput device 300 may not be able to distinguish between the scenarioillustrated in FIG. 4 where the finger stayed in contact with thesurface 308 and the scenario illustrated in FIG. 5 where a finger waslifted from the surface 308 and thereafter a finger was quickly placeddown on the surface 308. Without such a reliable determination, theinput device 300 will be unable to reliably generate the appropriateresponse.

This can lead to several different potential problems. For example, theinput device may not reliably “scroll” or “pan” as intended by the userin response to a motion across the surface. Instead, the motion acrossthe surface by the finger may be interpreted as a new “tap” at the newlocation of the finger and inadvertently activate a function associatedwith such a tap. As another example, pointing with an input object canbe misinterpreted as taps at a new location and vice versa. In suchcases misinterpreting an intended “tap” as pointing motion can causeunwanted cursor jumping when selection was instead intended by the user.

The embodiments described herein avoid these potential problems byproviding a mechanism for more reliably determining if an input objectdetected in a first image of sensor values and an input object detectedin a second image of sensor values remained in contact with the inputsurface between the first image and the second image. Specifically, byusing the force values from one or more force sensors to disambiguatewhether the input object remained in contact between the images. Thus,the input device 300 may be then configured to generate a first userinterface action in response to a determination that the input objectdetected in the second image of sensor values remained in contact withthe input surface between the first image and the second image andgenerate a second user interface action in response to a determinationthat the input object detected in the second image of sensor values didnot remain in contact with the input surface between the first image andthe second image.

As was noted above, many types of force sensors can be utilized toprovide force values to the processing system. By providing at least oneforce value between images generated by the sensor electrodes it can bemore reliably determined whether the input object detected in a firstimage remained in contact with the surface between images. Specifically,if applied force is detected between the consecutive images it can bemore reliably assumed that the input object remained in contact betweenimages and thus the correct user interface response can be more reliablygenerated.

Furthermore, as was discussed above many typical force sensors can beconfigured to provide force values at a relatively high rate.Specifically, because of the amount of time and processing typicallyrequired to generate a full capacitive image (that will include numerousrows or columns of values, each generated at a different time) the rateat which such images may be generated is limited. In contrast, manyforce sensors can generate force values at considerably greater rate.This is particularly true of some capacitive force sensors, where eachcapacitive measurement may be used to generate a force value. Thus, byusing such force sensors multiple force values can be generated betweeneach generated image. Generating and using multiple force values betweenimages can thus provide further ability to determine if an object hasremained in contact with the surface between images, or if instead theobject has lifted from the surface and the same or other object placedback down.

It should be noted that this is just one example of the type ofambiguity that can be potentially resolved through the use of forcevalues. In another example such force values can be used to determine ifan input object detected in a first image had actually initiallycontacted the input surface at a different location before it was firstsensed in an image. Turning now to FIGS. 6 and 7, the input device 300is illustrated with two such different exemplary input object scenarios.In FIG. 6, an input object (i.e., a finger 602) is illustrated with aninitial detected location at a position 604 and then moving across thesensing region 306 to the second position 606. In FIG. 7, an inputobject (i.e., a finger 602) is illustrated with an initial contactlocation at a contact position 608 and then moving across the sensingregion 306 from the position 604 to the second position 606. In bothscenarios the input object is first detected in an image at position 604and then subsequently detected in the next image at the second position606. However, the two scenarios differ as to where the actual initialcontact occurred.

Such a distinction can make a difference in applications where theresulting user interface action is dependent upon the location ofinitial contact by the input object. And without more information, theinput device 300 may not be able to determine that the input objectactually made initial contact at an earlier location than it was firstdetected in an image. Without such a reliable determination, the inputdevice 300 will be unable to reliably generate the appropriate response.

This can lead to several different potential problems. For example,where a resulting user interface action is dependent upon the locationof initial contact by the input object. As a specific example, in somecases a user interface may be configured to provide a pull-downinterface in response to a user initially contacting the sensor near anedge region and dragging the input object across the sensing region 306.Such pull-down interfaces can provide a variety of functions to theuser. However, in most embodiments such pull-down interfaces will onlybe activated when the initial contact location is determined be at ornear an edge region of the sensing region. Thus, if the initial contactlocation is inaccurately determined to not be near the edge thepull-down interface will not be activated. As noted above, with aquickly moving finger the input object may not be detected in an imageat its first true contact location (e.g., contact location 608) and mayinstead only be detected at a later position (e.g., position 604). Insuch a scenario the pull-down interface may incorrectly not be activatedwhen it was intended to be activated by the user.

It should be noted that in such embodiments it may be sufficient todetermine that a contact prior to detecting the input object in thefirst image did not occur prior to the object being detected in animage, or did not occur within a specified threshold distance prior tothe object being detected in the image. Stated another way, the lack offorce detection can be used to help make the disambiguation even if theinitial contact location was within an edge region. For example, in thescenario of FIG. 6 if no contact above a threshold level is detected inthe immediate time prior to having detected the image at position 604then it can be reliably determined that contact in the edge region didnot occur and an edge region specific response need not be generated.

As another example, in some embodiments a gesture may be performed whenan initial contact location is within a distance threshold or some othercriteria such as speed of motion. In this case the embodiments describedherein can be used to determine if such an initial contact within athreshold occurred. Again, the input device can be configured to notperform the gesture when an initial contact is not detected immediatelyprior the input object being detected in an image, and where the inputobject was detected outside the specified distance threshold in thatimage. Alternatively, the input device can be configured perform thegesture only when the initial contact is affirmatively determined to bewithin the specified distance threshold. For example, when an initialcontact is determined to have occurred prior to detecting the inputobject in the first image, and that initial contact location is withinthe specified distance threshold. Or alternatively, when the inputobject is detected within the specified range in the first image and noforce values indicate that the actual initial contact occurred outsidethe specified range. In each of these various embodiments the forcevalues are used with the images to determine the gesture intended by theuser.

The embodiments described herein avoid these potential problems byproviding a mechanism for more reliably determining an initial contactlocation for an input object first detected in a first image of sensorvalues based at least in part on at least one force value preceding thefirst image of sensor values and the first image of sensor values.Specifically, by using the force values from one or more force sensorsto disambiguate whether the input object actually made contact prior tobeing first detected in an image, and determining an estimate of thelocation of the initial contact. As was noted above, many types of forcesensors can be utilized to provide force values to the processingsystem. By providing at least one force value between images generatedby the sensor electrodes those force values can be used to determine ifan input object made contact before it was detected in an image.Specifically, if applied force is detected shortly before the object wasdetected in an image it can be more reliably assumed that the inputobject may have actually contacted the input surface at a differentlocation.

Furthermore, as was discussed above many typical force sensors can beconfigured to provide force values at a relatively high rate.Specifically, because of the amount of time and processing typicallyrequired to generate a full capacitive image (that will include numerousrows or columns of values, each generated at a different time) the rateat which such images may be generated is limited. In contrast, manyforce sensors can generate force values at considerably higher rate.This is particularly true of some capacitive force sensors, where eachcapacitive measurement may be used to generate a force value. Thus, byusing such force sensors multiple force values can be generated betweeneach generated image. Generating and using multiple force values betweenimages can thus provide further ability to determine if an object hadinitially contacted the surface prior to be detected in an image.

A variety of different techniques can be used to determine an initialcontact location for an input object first detected in a first image ofsensor values based at least in part on at least one force valuepreceding the first image of sensor values and the first image of sensorvalues. As one example, locations of the input object in the first imageand the second image are used and the time difference between suchimages to estimate a rate of motion of the input object across thesensing region. By estimating the rate of motion of the input object,and the time that contact was detected using the force sensor, anestimate of the initial contact location can be determined.

Turning now to FIG. 8, the input device 300 is illustrated with position604, second position 606 and contact position 608 illustrated as crossesin the sensing region 306. As can be seen in FIG. 8, position 604 andsecond position 606 are separated by a distance D1, while contactposition 608 and position 604 are separated by a distance D2. The timeof the input object being at position 604, and the location of position604 can be determined from the first image. Likewise, the time of theinput object being at second position 606, and the location of secondposition 606 can be determined from the second image. Finally, the timeof contact at contact position 608 can be determined from the forcevalues.

With these values determined the position of the input object contact(i.e., contact position 608) can be accurately estimated. Specifically,because the distance D2 can be determined and used to estimate thevelocity of the input object as it moved from position 604 and secondposition 606 the distance D1 can be estimated by assuming the velocitywas relatively constant between all three positions. Furthermore, thelocation of contact position 606 can be estimated by assuming that theinput object was traveling in a relatively straight line. Thus, fromthese determinations it can be determined if the initial contact atcontact position 606 likely occurred in a region that would indicate aspecific user interface action was intended to be performed.

For example, it can be determined if the initial contact position 608occurred in an edge region proximate an edge of the sensor region 306.FIG. 8 illustrates the boundary of an exemplary edge region with line610. As described above, such edge regions are commonly implemented tosupport a variety of user interface functions. For example, to provide apull-down interface in response to a user initially contacting thesensor in the edge region and dragging the input object across thesensing region 306. In this case, by determining the location of contactposition 608 it can be more reliably determined that the user intendedto initiate such a pull-down interface. Thus, if the initial contactposition 608 is determined to have occurred in the edge region thepull-down interface can be activated even though the input object wasnot detected in a capacitive image until it was outside the edge regionat position 604. The input device 300 can thus more reliably respond toquickly moving fingers and other input objects that may not be detectedat their initial locations.

As described above, the force values provided by the force sensors canbe used with the images of sensor values to provide a variety ofpositional information. For example, positional information for an inputobject detected in a first image of sensor values based at least in parton the first image of sensor values and the force values. Thispositional information may be used to distinguish between a variety ofdifferent user interface actions. For example, determining if an inputobject detected in a first image of sensor values and an input objectdetected in a second image of sensor values performed a swipe across theinput surface while remaining in contact with the input surface betweenthe first image and the second image, or instead if the input objectdetected in the first image lifted from the input surface between thefirst image and the second image. As another example, determining if aninitial contact location for an input object first detected in a firstimage of sensor values based at least in part on at least one forcevalue preceding the first image of sensor values and the first image ofsensor values.

The force values provide by the force sensors can also be used foradditional functions. For example, one or more force values maythemselves be used to generate positional information for the inputobject. This can be done using a variety of techniques, such as byestimating a deflection response or deformation response from the forcevalues. Examples of these techniques are described in U.S. patentapplication Ser. No. 12/729,969, filed Mar. 23, 2010, entitledDEPRESSABLE TOUCH SENSOR; U.S. patent application Ser. No. 12/948,455,filed Nov. 17, 2010, entitled SYSTEM AND METHOD FOR DETERMINING OBJECTINFORMATION USING AN ESTIMATED DEFLECTION RESPONSE; U.S. patentapplication Ser. No. 12/968,000 filed Dec. 14, 2010, entitled SYSTEM ANDMETHOD FOR DETERMINING OBJECT INFORMATION USING AN ESTIMATED RIGIDMOTION RESPONSE; and U.S. patent application Ser. No. 13/316,279, filedDec. 9, 2011, entitled INPUT DEVICE WITH FORCE SENSING.

Thus, the embodiments and examples set forth herein were presented inorder to best explain the present invention and its particularapplication and to thereby enable those skilled in the art to make anduse the invention. However, those skilled in the art will recognize thatthe foregoing description and examples have been presented for thepurposes of illustration and example only. The description as set forthis not intended to be exhaustive or to limit the invention to theprecise form disclosed.

What is claimed is:
 1. A processing system for an input device, the processing system comprising: a sensor module comprising sensor circuitry configured to: operate a plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface at a first rate; operate at least one force sensor to generate force values indicative of force applied to the input surface at a second rate; a determination module configured to: determine if an input object detected in a first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values.
 2. The processing system of claim 1 wherein the second rate is greater than the first rate.
 3. The processing system of claim 1 wherein the first image of sensor values and the second image of second values comprise consecutive images generated by the determination module.
 4. The processing system of claim 1 wherein the force sensor comprises a capacitive force sensor.
 5. The processing system of claim 1 wherein the determination module is further configured to determine positional information for an input object based on the force values.
 6. The processing system of claim 1 wherein the determination module is further configured to determine an initial contact location for an input object first detected in the first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values.
 7. The processing system of claim 1 wherein the determination module is configured to generate a first user interface action in response to a determination that the input object detected in the second image of sensor values remained in contact with the input surface between the first image and the second image and generate a second user interface action in response to a determination that the input object detected in the second image of sensor values did not remain in contact with the input surface between the first image and the second image.
 8. A processing system for an input device, the processing system comprising: a sensor module comprising sensor circuitry configured to: operate a plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface at a first rate; operate at least one force sensor to generate force values indicative of force applied to the input surface at a second rate; a determination module configured to: determine an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values.
 9. The processing system of claim 8 wherein the second rate is greater than the first rate.
 10. The processing system of claim 8 wherein the determination module is further configured to initiate an edge user interface action based on the initial contact location in response to the initial contact location being in an edge region.
 11. The processing system of claim 8 wherein the determination module is further configured to not initiate an edge user interface action in response to a determination that an initial contact within an edge region did not occur prior to the first image of sensor values.
 12. The processing system of claim 8 wherein the force sensor comprises a capacitive force sensor.
 13. The processing system of claim 8 wherein the determination module is further configured to generate positional information for the input object using the force values.
 14. The processing system of claim 8 wherein the determination module is further configured to determine if an input object detected in the first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values.
 15. An input device comprising: an input surface a plurality of capacitive sensor electrodes proximate to the input surface; at least one force sensor coupled to the input surface; a processing system operatively coupled to the plurality of capacitive sensor electrodes and the at least one force sensor, the processing system configured to: operate the plurality of capacitive sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to the input surface at a first rate; operate the at least one force sensor to generate force values indicative of force applied to the input surface at a second rate; determine if an input object detected in a first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values.
 16. The input device of claim 15 wherein the second rate is greater than the first rate.
 17. The input device of claim 15 wherein the first image of sensor values and the second image of second values comprise consecutive images generated by the processing system.
 18. The input device of claim 15 wherein the force sensor comprises a capacitive force sensor.
 19. The input device of claim 15 wherein the processing system is further configured to determine positional information for an input object based on the force values.
 20. The input device of claim 15 wherein the processing system is further configured to determine an initial contact location for an input object first detected in the first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values.
 21. The input device of claim 15 wherein the processing system is configured to generate a first user interface action in response to a determination that the input object detected in the second image of sensor values remained in contact with the input surface between the first image and the second image and generate a second user interface action in response to a determination that the input object detected in the second image of sensor values did not remain in contact with the input surface between the first image and the second image.
 22. A method of determining input in an input device, the method comprising: operating a plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface at a first rate; operating at least one force sensor to generate force values indicative of force applied to the input surface at a second rate; determining an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values; and generating a user interface action based at least in part on the initial contact location.
 23. The method of claim 22 wherein the second rate is greater than the first rate.
 24. The method of claim 22 wherein the generating the user interface action based at least in part on the initial contact location comprises initiating an edge user interface action based on the initial contact location in response to the initial contact location being in an edge region.
 25. The method of claim 22 wherein the force sensor comprises a capacitive force sensor.
 26. The method of claim 22 further comprising generating positional information for the input object using the force values.
 27. The method of claim 22 further comprising determining if an input object detected in the first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values. 